BR 3392687: clang miscompiles offsetin() for uninitialized pointer
BR 3392687: clang miscompiles offsetin() for uninitialized pointer

The actual pointer value in offsetin() cancels out, but clang still
miscompiles offsetin() for an uninitialized pointer, considering the
value to be completely undefined. Initialize pointer being passed to
offsetin() to make clang happy; both the gcc and clang optimizers
discover later in the code that the initialization is unused and
removes it from the code.

Although technically undefined behavior, this is in my opinion a
severe quality of implementation bug in clang, and I will file a bug
report accordingly.

Reported-by: Jasper Lievisse Adriaanse <cc229b55a81e521f337617e823df205da993cca5@jasper.la>
Reported-by: David Bohman <007b11276010741334bf50afba333b8e35952704@gmail.com>
Signed-off-by: H. Peter Anvin (Intel) <8a453bad9912ffe59bc0f0b8abe03df9be19379e@zytor.com>

techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm